-LRB- CNN -RRB- -- Islamist militants in Somalia have warned a United Nations agency to buy food from Somali farmers or stop sending aid to the impoverished African country .

`` WFP -LSB- World Food Programme -RSB- causes many problems for the local Somali farmers by importing food from outside Somalia and that discourages the Somali farmers , '' al-Shabaab said in a statement .

`` So the WFP should buy its supposed food distribution from Somali farmers or stop its operations in Somalia . ''

The militia also warned local Somali contractors who help distribute WFP food aid to stop helping the U.N. agency by January 1 .

The warning could be a desperate measure by al-Shabaab , which is reportedly facing financial difficulties following the withdrawal of Ethiopian forces last year . The Ethiopian invasion of Somalia had outraged many members of the Somali diaspora who had sent money to al-Shabaab , which had vowed to kick out the invading forces .

Al-Shabaab has now waged a bloody insurgency against the U.N.-backed government of transitional President Sheikh Sharif Sheikh Ahmed .

The WFP is aware of the report , according to a spokesman for the agency who would not say whether WFP was in touch with al-Shabaab .

`` WFP is working in Somalia because the country can not currently support the food needs of its population , '' Greg Barrow told CNN .

Somalia is in the middle of the worst humanitarian crisis since the famine of the early 1990s , with half of its population -- nearly 4 million people -- in need of food aid , according to the WFP .

Somalia is also one of the most dangerous places in the world : four WFP staff members were killed between August 2008 and January 2009 .

Nevertheless , the aid agency said it increased its operations during the first half of this year , providing assistance to nearly 3 million people .

CNN 's Alden Mahler Levine and Journalist Mohammed Amiin Adow contributed to this report

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Islamic militants say World Food Programme causes problems by importing food from outside

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Al-Shabaab warns contractors who help distribute food to stop helping the U.N. agency

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Somalia is in the middle of its worst crisis since the famine of the 1990s , according to the WFP